1. Field of the Invention
The present invention relates to a camera system. The camera system of the present invention is applicable, for example, to a three-dimensional camera for monitoring, a built-in three-dimensional camera in a video see-through head mounted display (HMD), and a three-dimensional camera to be used as a robot eye.
2. Description of the Related Art
When obtaining a parallax image by using multiple photographing systems, if the entrance pupil position of each photographing system varies depending on the object distance or the zoom position, it is impossible to obtain a satisfactory parallax image for three-dimensional viewing.
In view of this, according to Japanese Patent Application Laid-Open No. H10-145649 (which corresponds to U.S. Pat. No. 5,937,212), in order to obtain an accurate parallax image, the entrance pupil is arranged at the position in the zoom lens nearest to the object, that is, the aperture stop is arranged on the front side of the zoom lens, thereby preventing variation in the entrance pupil position due to zooming. Further, according to Japanese Patent Application Laid-Open No. H10-145649, right-hand and left-hand photographing systems are configured so as to be rotatable around the respective entrance pupil center positions of the photographing system. Thus, when zooming or adjusting the angle of convergence, there is no need to correct variation in the entrance pupil positions of the photographing systems.
However, when the aperture stop is arranged at the position in the zoom lens nearest to the object as in Japanese Patent Application Laid-Open No. H10-145649, the size of the zoom lens becomes rather large.